This application is partly based on and claims the priority under 35 U.S.C. xc2xa7119 of German Patent Application 198 34 702.2, filed on Jul. 31, 1998, through prior U.S. application Ser. No. 09/366,036, filed on Aug. 2, 1999. The entire disclosures of the above identified German Patent Application and prior U.S. Application are incorporated herein by reference.
The invention relates to a riveting apparatus for riveting large surface area components having a curved contour to fabricate a barrel-shaped structure such as an aircraft fuselage.
Automatic and semi-automatic robotic riveting apparatus are known for connecting large surface area components using rivets. Such known apparatus are suitable for the fabrication of aircraft fuselage shells and other barrel-shaped or cylindrical structures that are fabricated from a plurality of individual curved components having large surface areas. For example, German Patent 35 35 761 and corresponding U.S. Pat. No. 4,762,261 (Hawly et al.) disclose an automatic robotic riveting apparatus by means of which curved workpieces having large surface areas can be rivet-fastened or the like. The disclosure of U.S. Pat. No. 4,762,261 is incorporated herein by reference.
The known riveting apparatus comprises a machine frame in which a workpiece is mounted so as to be movable along the X-axis. Two riveting systems or tool carriers that cooperate with each other for carrying out the riveting process are respectively arranged on a riveting positioning frame that is movable in the Z-direction, while the riveting systems or tool carriers are selectively positionable in the Y-direction and tiltable about the X-axis. One of the riveting systems comprises a riveting device including all the necessary tools for boring rivet holes, feeding and sinking rivets, and counterholding during a rivet closing process. The other riveting system comprises a pressure sleeve, a rivet snap or anvil, and a counterholder for forming the closing head of each respective rivet. In order to carry out a riveting process, the two riveting systems are driven and positioned to the corresponding rivet location in a computer aided or computer guided manner, and then the various steps of the riveting process are carried out and coordinated also in a computer aided manner.
It is a disadvantage of this known automatic riveting robot that it can only be used in a limited field of applications due to its high structural mass. A further disadvantage is that only certain rivet connections can be produced by this conventional automatic riveting robot, because the riveting systems are not individually movable in all spacial axes. Further disadvantages result because the workpieces, for example aircraft fuselage shell components, must be slidingly pushed or advanced in the X-axis direction during the riveting process, which requires a rather heavy and complicated holding jig or support frame structure for precisely positioning the large workpieces.
Another riveting apparatus suitable for forming a rivet connection for large surface area components is disclosed in German Patent 37 15 927 and corresponding U.S. Pat. No. 4,854,491 (Stoewer). The disclosure of U.S. Pat. No. 4,854,491 is incorporated herein by reference. This known riveting apparatus comprises two mechanically separated apparatus parts, namely one respective apparatus part on the primary or set head side of the rivet and another apparatus part on the closing head side of the rivet. Each one of these apparatus parts respectively essentially comprises a machine guide arrangement carrying a tool unit. A computer is provided to control the positioning as well as the working steps carried out in the process of forming and preparing the rivet holes and then inserting rivets into the holes, as well as closing the rivets.
In this known riveting apparatus, for carrying out the riveting operation, machine guide arrangements are provided respectively on both sides of the components or workpieces that are to be rivet-connected to each other and that are held in a supporting frame. The machine guide arrangements and respective apparatus parts on the two sides of the workpieces are necessary to allow the respective tool units to be guided to and positioned at the respective riveting locations. However, in practice, it is very difficult and complicated or even impossible to properly arrange the respective machine guide arrangements for forming rivets at particular individual rivet locations, especially in the area within an aircraft fuselage for forming a lengthwise or transverse seam of the fuselage. This is especially true because the interior of the fuselage shell comprises frames, stringers, spars, ribs and struts and the like, which represent obstacles or obstructions around which the machine guide arrangement and the respective tool units must be moved, and which in some cases completely block access to the required rivet locations.
U.S. Pat. No. 6,098,260 (Sarh) discloses a system for riveting radial or circumferential joints of an aircraft fuselage. In this known system, an outer riveting apparatus includes crescent-shaped base members that are supported on the fuselage itself and are directly secured to the fuselage by suction cups or the like, and a first riveting device that is movably supported on the crescent-shaped base members, so as to ride along the base members while fastening rivets along a circumferential joint of the fuselage. Further in the known system, an inner riveting apparatus includes a base unit or base plate that is mounted on the floor beams of the interior of the fuselage itself, and a second riveting device that cooperates from inside the fuselage with the first riveting device outside the fuselage to fasten the rivets along the respective circumferential joint.
Thus, both the inner apparatus and the outer apparatus of the known system of U.S. Pat. No. 6,098,260 are mounted on and fully supported by the fuselage that is being assembled. This limits the mobility of the apparatus relative to the fuselage. Namely, the supporting base of the outer apparatus itself is not mobile relative to the fuselage. Instead, a crane is necessary to lift the outer apparatus and move it from one circumferential fuselage joint to the next, and therefore the system is not suited to riveting longitudinal joints. Moreover, the known arrangement must have its crescent-shape adapted exactly to the contour of the particular type of fuselage being assembled, and presents the danger that the weight of the two apparatus will deform or misalign the aircraft sections being joined. Other known systems in which the inner and/or outer riveting apparatus are mounted and supported on the fuselage itself suffer the same disadvantages.
In view of the above it is an object of the invention to provide a two-part riveting apparatus for riveting barrel-shaped components, which makes it possible to carry out a flexible or adaptable positioning of the tool units on or relative to the respective workpiece in longitudinal and circumferential directions, and especially at previously inaccessible or difficult to access rivet locations which are at least partially obstructed due to strengthening components or equipment mounting components, such as frames, stringers, spars, ribs, struts or the like in the interiors of a barrel-shaped structure. Moreover, it is an object of the invention to provide such an apparatus that is fully independent of the workpiece being assembled, i.e. is not supported or mounted on the workpiece, but instead is supported and mounted independently from the workpiece. Another object of the invention is to provide an apparatus that can fully automatically carry out the riveting operation with great precision in a computer controller manner. The invention further aims to avoid or overcome the disadvantages of the prior art, and to achieve additional advantages, as apparent from the present specification.
The above objects have been achieved according to the invention in a joining apparatus and particularly a riveting apparatus suitable for riveting together curved large surface area components to form a manufactured product such as an aircraft fuselage, including a barrel-shaped structure and possibly further including a floor structure or the like mounted inside the barrel-shaped structure. According to the invention, the riveting apparatus includes an outer apparatus part arranged externally around the barrel-shaped structure, an internal apparatus part reaching inside the barrel-shaped structure, and a control unit for controlling the operation of the two apparatus parts for carrying out the riveting process.
The outer part of the apparatus comprises an annular machine guide arrangement that is arranged externally encircling the barrel-shaped structure and that is relatively movable along the lengthwise X-axis of the barrel-shaped structure. Particularly, either the annular machine guide arrangement or the barrel-shaped structure is movable in the X-direction relative to the other. The outer part further comprises at least one riveting machine system including the necessary tools or devices for producing and preparing rivet holes, supplying and inserting rivets into the rivet holes, and then completing the riveting process. The riveting machine system is movably arranged on the machine guide arrangement so as to be selectively movable to preselected rivet locations. These rivet locations are defined by stored data or input data of the control unit so that the rivet machine system is moved to the respective rivet locations in succession in a computer aided or computer controlled manner. Instead of the riveting machine, the outer part may include a welding machine or an adhesive bonding machine or other types of joining machines known in the art.
The inner part of the riveting apparatus comprises a mounting frame that is relatively movable along the lengthwise X-axis of the barrel-shaped structure, as well as a multi-axis movable controlled riveting robot arranged on the mounting frame. The riveting robot includes a working head with the necessary tools for carrying out one side of the riveting operation (or other joining operation such as a welding operation, adhesive bonding operation, or the like). The mounting frame and the riveting robot cooperate with one another and are moved in a computer aided or computer controlled manner so as to move the working head of the riveting robot selectively to the respective working positions inside the barrel-shaped structure corresponding to the rivet locations defined on the outside of the barrel-shaped structure. Specifically, the control unit provides the necessary control signals to the outer part of the apparatus and the inner part of the apparatus, so as to ensure the coordinated and aligned positioning of the outer and inner parts of the apparatus respectively at a selected rivet location.
In the present apparatus, the inner part and the outer part are each supported independently of the manufactured product including the barrel-shaped structure being assembled, and are independently movable and arrangeable under a computer aided guidance relative to the manufactured product. Either the inner part and the outer part of the apparatus, or the manufactured product itself, may be movable relative to the other in the longitudinal X-direction. In this manner, each individual part of the apparatus, i.e. the outer part and the inner part, can be moved as necessary and the tools can be oriented and positioned with the required degrees of freedom of motion so as to efficiently move or reach around any obstructions and thereby reach difficult to access rivet locations in a fully automatic manner. This makes it possible to achieve an economically advantageous riveted seam fabrication of curved, large surface area components to form a barrel-shaped structure such as an aircraft fuselage.
The above objects have further been achieved according to the invention in a method of joining shell components to form a manufactured product including a barrel-shaped structure. In a first embodiment of the method, the inner and outer apparatus parts are movable relative to an assembly hall or shop in which the assembly is carried out, while the manufactured product remains stationary relative to the assembly hall or shop. In a second embodiment of the method, the manufactured product is moved relative to the shop, while at least the outer apparatus part and preferably also the inner apparatus part remain stationary relative to the shop. In both embodiments, the motion, alignment and positioning of the barrel-shaped structure and/or the apparatus parts are preferably numerically controlled, e.g. by an automated, computer control executing a pre-established program.
In the first embodiment of the method, the barrel-shaped structure that is being assembled is supported on the shop floor by adjustable supports that adjust the height, orientation and alignment of the structure, while the outer apparatus part is movable along rails on the shop floor, and the inner apparatus part is either standing on the shop floor or also movable on rails on the floor. Starting from a first assembled section, further sections are joined onto the structure as follows. Curved shell components for the next section are moved into position, adjusted and supported in a respective assembly station. The shell components are preferably tacked or held together, and then the circumferential joint adjoining the structure is riveted by the cooperating outer and inner riveting tools, whereby the outer and inner apparatus parts have moved to the appropriate location in the longitudinal X-direction to achieve the riveting of this joint. Then, the structure being assembled remains stationary, and the outer apparatus part moves along the X-direction (while the robot of the inner apparatus part correspondingly moves the inner riveting tool) to rivet the respective longitudinal joints between adjoining ones of the shell components to finish joining this section.
While the structure being assembled still remains stationary, the shell components for the next section are moved into position, adjusted and supported in a next respective assembly station. These shell components are tacked or held together, and then they are joined to the previously riveted section by the inner and outer riveting tools cooperating to rivet the circumferential joint. Next, the outer apparatus part moves along the X-direction (while the robot of the inner apparatus part correspondingly moves the inner riveting tool) to rivet the respective longitudinal joints between adjoining ones of the shell components to finish joining this newest section.
In this manner, the barrel-shaped structure remains stationary but xe2x80x9cgrowsxe2x80x9d along the x-direction by the rivet-joining of successive sections. To add each section to the structure, the shell components forming the new section are first positioned and tacked, then joined to the structure along the circumferential joint, and finally the longitudinal joints between the shell components are riveted to finish this respective section. Throughout this process, the structure remains stationary, while the inner and outer apparatus parts move along the shop floor as necessary in the direction of xe2x80x9cgrowthxe2x80x9d of the structure in the X-direction, and the inner and outer riveting tools additionally move in the circumferential direction as necessary to carry out the riveting.
In the second embodiment, the barrel-shaped structure being assembled is supported and adjusted on movable carriages or pallets, for example that are movable along rails on the shop floor, while the outer and inner machine parts remain fixed relative to the shop floor. The shell components for each respective successive section are moved into place, positioned and held or tacked in a defined assembly station. The apparatus rivets the circumferential joint, and then the structure and next section are moved (by means of the moving carriages or pallets) through the outer apparatus part while it carries out riveting along the longitudinal joints. The joining steps are similar to the first embodiment, except that here the structure is moved relative to the shop floor and the riveting apparatus, while the apparatus remains stationary relative to the shop floor (this means that the supporting frames of the apparatus are stationary while of course the riveting tools are moved relative to the supporting frames as necessary along the joints to be riveted, e.g. in the circumferential direction).